Mineraloid

Obsidian

Volcanic glass

Black Obsidian

Volcanic Glass

Amber

Succinite (Organic Mineraloid)

Obsidian

Volcanic glass

Black Obsidian

Volcanic Glass (Amorphous SiO2)

Obsidian

Volcanic Glass (Amorphous SiO2)

Obsidian

Volcanic Glass

Black Obsidian

Volcanic Glass

Obsidian

Volcanic glass

Obsidian

Volcanic Glass

Obsidian

Volcanic Glass

Obsidian

Volcanic Glass

Anthracite Coal

Anthracite (Carbon-rich mineraloid)

Amber

Succinite (Organic Mineraloid) - C10H16O

Obsidian

Volcanic Glass (Silica-rich glass)

Obsidian

Volcanic glass

Pearl

Organic Mineraloid (CaCO3 + Conchiolin)

Obsidian

Volcanic Glass

Obsidian

Volcanic glass

Obsidian

Volcanic Glass

Obsidian

Volcanic Glass

Mahogany Obsidian

Volcanic glass (high silica) with inclusions of Magnetite or Hematite

Obsidian

Volcanic glass (SiO2 + impurities)

Obsidian

Volcanic Glass (Amorphous SiO2)

Obsidian

Volcanic Glass

Limonite or Ironstone Nodule

FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide)

Black Obsidian

Volcanic Glass (predominantly SiO2)

Obsidian

Volcanic Glass

Black Obsidian

Volcanic Glass (Amorphous SiO2)

Black Obsidian

Volcanic Glass (Amorphous SiO2 with trace impurities)

Obsidian

Volcanic Glass (Amorphous silicon dioxide with impurities)

Black Obsidian

Volcanic glass

Obsidian

Volcanic Glass

Obsidian

Volcanic Glass (SiO2 + impurities)

Fulgurite

Fulgurite (Lechatelierite)

Black Obsidian

Volcanic Glass (SiO2 + impurities)

Obsidian

Volcanic Glass

Tumbled black stone, likely black obsidian

Obsidian — volcanic glass, primarily SiO₂

Gold Sheen Obsidian

Volcanic Glass (SiO2 + Fe3O4 / Gas Inclusions)

Abalone Shell (Nacre)

Aragonite (CaCO3) - Biogenic Mineral

Obsidian

Volcanic glass

Limonite (Ironstone)

Limonite (mixture of hydrated iron oxides, primarily Goethite α-FeO(OH))